Worldwide Benchmarking of ITER Internal Tin ${\rm Nb}_{3}{\rm Sn}$ and NbTi Strands Test Facilities

Abstract

The ITER machine will require approximately 250 tons of NbTi strands and 500 tons of Nb3Sn strands. NbTi will be used in the Poloidal Field (PF) coils, Correction Coils (CC) and feeder busbars, whereas Nb3Sn will be used in the Central Solenoid (CS) and Toroidal Field (TF) coils. The large amount of superconducting strands needed requires worldwide procurement, involving suppliers from six of the seven ITER Domestic Agencies (DAs). To ensure reliable test results, it is necessary to benchmark the test facilities at each supplier and at each DA reference laboratory for physical and superconducting properties measurement, as well as sample preparation techniques. Following previous benchmarking efforts related to ITER procurement in the mid-1990's and to supplier and DA laboratory qualification performed on bronze route Nb3Sn strands in 2009, we report here the latest rounds on internal tin Nb3Sn and NbTi strands. Ten participants from five DAs (China, EU, South Korea, Russia, and the U.S.) together with CERN (the ITER Organisation's reference laboratory) took part in the benchmarking of internal tin Nb3Sn strands, and six participants from China and Russia, plus CERN, participated in the benchmarking of NbTi strands.